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51 Cards in this Set

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  • Back
How is histamine made?
histidine -> (histidine decarboxylase) -> histamine
Where in the body is histamine in highest concentrations?
lung
skin
stomach
gut
Name three places where histamine is stored?
mast cells (tissue phagocytes) and basophils (blood phagocytes)
CNS
mucosal layer of GI tract
The histamine content of most tissues is related to their ... content?
mast cell content
Why is histamine inert in mast cells?
its stored in secretory granules and linked to proteoglycans
How does histamine negatively modulate its own release?
through H2 receptors on mast cells
When the histamine content of mast cells is depreciated, how long does it take for the concentration to return to normal
it can take weeks
Are allergic reactions causing histamine release cytolytic?
no
Name 5 chemicals that cause chemical histamine release
morphine
tubocurarine
succinylcholine
vancomycin (red man syndrome)
radiocontrast
are chemicals causing histamine release cytolytic?
no
is energy required for histamine release mediated cellular injury
no
Give 5 states in which symptoms from histamine toxicity (headache, flushing, hypotension, and nausea) are also seen
1. mastocytosis
2. myelogenous leukemia
3. gastric carcinoid tumors
4. food poisoning from spoiled scombroid fish
5. red wine consumption when people have reduced ability to degrade histamine
What superfamily of receptors do histamine receptors belong to
7 transmembrane G protein-linked receptors

[like rhodopsin ;)]
receptor in sm mm, endothelium and brain
signals PLC --> IP3, DAG, NO, and PLA
H1
receptor in gastric mucosa, brain, cardiac muscle, mast cells
signals cAMP, inhibition of arachidonic acid release, Ca
H2
receptor in presynaptic, brain, myenteric plexus, peripheral neurons
signals Ca, inhibits cAMP
H3
receptor in bone marrow, peripheral hematopoietic cells
signals Ca, inhibits cAMP
H4
through what histamine receptors is vasodilation mediated?
H1: endothelial cells
H2: vascular sm mm
through what histamine receptors is increased cardiac contractility and increased pacemaker rate mediated?
H2
Through what histamine receptor is contraction of intestinal sm mm and increased GI motility mediated?
H1
Histamine receptor involved with bronchoconstriction
H1
What may happen in anaphylactic pregnant women?
may abort due to uterine contraction
Histamine receptor involved in stimulant of sensory nerve endings- pain and itching
H1
Histamine receptor involved in stimulant of gastric acid secretion from parietal cells?
H2
Histamine receptor involved in triple wheal and flare response to intradermal histamine injection
H1
Name a physiologic antagonist that acts through a different receptor and opposes action of histamine?
epinephrine
Name two drugs that can inhibit histamine release from mast cells?
cromolyn
nedocromil
histamine receptor antagonists act at which receptors?>
H1 and H2, they are competitive
Describe first generation antihistamines
small --> cross BBB
cross react w/ other receptors
available OTC
sedation as side effect
Describe second generation antihistamines
larger and lipophobic
more specific for H1
prescription only (except Claritin)
non-sedating
chlorpheniramine (chlortrimeton)
1st generation antihistamine
clemastine
1st generation antihistamine
dimenhydrinate
(dramamine)
1st generation antihistamine
diphenhydramine
1st generation antihistamine
(benadryl)
doxylamine
1st generation antihistamine
hydroxine
1st generation antihistamine
meclizine
1st generation antihistamine
(antivert)
promethazine
(phenergan)
1st generation antihistamine
fexofenadine
2nd generation antihistamine
(allegra)
cetirizine
2nd generation antihistamine
loratadine
2nd generation antihistamine
(claritin)
Name two antihistamines used for sleep induction
diphenhydramine
doxylamine
only antihistamine approved antitussive
diphenhydramine
antihistamine most widely used for Parkinson's disease
diphenhydramine
three antihistamines to treat vertigo/motion sickness
meclizine (Antivert)
promethazine (Phenergan)
dimenhydrinate (Dramamine)
When do antihistamines reach peak plasma concentration
When do antihistamines reach peak effectiveness
2 hrs after oral administration

5-7 hrs after oral administration
All 1st generation and most 2nd generation antihistamines are metabolized by which hepatic cytochrome?
P450
Who eliminates antihistamines faster- adults or kids?
kids
Name two 2nd generation antihistamines taken off the market
astemizole (hismanal)
terfenadine (seldane)
Name two antihistamines thought to be of lower risk to take during pregnancy
dimenhydrinate
loratadine
Name four H2 receptor antagonists
cimetidine (tagamet)
famotidine (pepcid)
nizatidine (axid)
ranitidine (zantac)